1. Technical Field
The present invention relates to a method of electrophoresis particles, electrophoresis particles, electrophoresis dispersion liquid, an electrophoresis sheet, an electrophoresis device, and an electronic apparatus.
2. Related Art
In general, if an electric field is applied to a dispersion system in which fine particles are dispersed in liquid, the fine particles move (migrate) in the liquid by Coulomb's force. This phenomenon is called electrophoresis, and recently there has been attention to an electrophoresis display device that displays desired information (image) by using the electrophoresis, as a new display device.
The electrophoresis display device has a characteristic of maintaining display in a state of the application of a voltage is stopped, having a wide viewing angle, performing display at high contrast with low power consumption, and the like.
In addition, since the electrophoresis display device is a non-light emitting-type device, it is friendly to eyes compared with light emitting-type devices such as a cathode-ray tube.
Such an electrophoresis display device is known for including liquid in which electrophoresis particles are dispersed in a solvent, as electrophoresis dispersion liquid provided between a pair of substrates including electrodes.
In the electrophoresis dispersion liquid configured as above, particles including positive charges and negative charges are used as the electrophoresis particles, and accordingly, desired information (image) can be displayed by applying a voltage between the pair of substrates (electrodes).
Here, as electrophoresis particles 501, particles including coating layers 503 in which macromolecules 533 are bonded to base particles 502 are used (see FIG. 7). According to the configuration of including the coating layers 503 (the macromolecules 533), the electrophoresis particles 501 can be dispersed and charged in the electrophoresis dispersion liquid.
In addition, the electrophoresis particles configured as described above are manufactured as described below, for example, by using an atom transfer radical polymerization reaction (ATRP).
That is, the base particles 502 are prepared, silane coupling agents 531 with polymerization initiation groups are bonded to the surfaces of the base particles 502, polymerization portions 532 in which monomers are polymerized by the living radical polymerization with the polymerization initiation groups as starting points are formed, and the macromolecules (polymers) 533 are provided so that the electrophoresis particles 501 to which characteristics such as electrostatic properties or dispersibility is applied are prepared (see JPA-2013-156381).
However, in the electrophoresis particles 501 manufactured by using the ATRP, the macromolecules 533 are generated by forming the polymerization portion 532 according to the polymerization of monomers with polymerization initiation groups included in the silane coupling agent boned to the surfaces of the base particles 502, as starting points. At this point, according to the concentration of the silane coupling agents which are bonded to the base particles 502, and the kind of monomers, molecular weights of the polymerization portions 532 in the generated macromolecules 533, that is, polymerization degrees of the monomers, have irregularities among adjacent polymerization portions in some cases.
Therefore, uniform dispersion properties may not be obtained among a plurality of electrophoresis particles included in the electrophoresis dispersion liquid.